Beijing is "gravely concerned" about the prospect of "unilateral military actions" against Syria, adding no measures should be taken until it is clear who, if anyone, had used chemical weapons in the country.
China, a veto-wielding permanent member of the United Nations Security Council, has consistently called for a political solution to the Syrian crisis.
Over the course of the conflict it has joined with fellow UN Security Council member Russia in blocking resolutions supported by Washington and its allies.
"We are gravely concerned that some country may take unilateral military actions," foreign ministry spokesman Hong Lei told reporters on Monday at a regular briefing, referring indirectly to the US.
Hong said US officials had shared information with China about the situation.
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"The US side has briefed China about the US evidence on chemical weapons used in Syria as well as relevant decisions made by the US," he said.
US Secretary of State John Kerry said on Sunday that Washington has proof the Syrian regime used sarin gas in a deadly attack last month.
President Barack Obama is building a case for US military strikes against the regime of President Bashar al-Assad. The US appeared ready to strike without congressional approval, but Obama reversed course and asked legislators to vote on an attack.
Hong said that Beijing was opposed to "whoever uses chemical weapons" and backed the UN in "carrying out an independent, impartial, objective and professional investigation".
He also said any action taken by the international community should be based on investigation outcomes.
"The results should tell us whether chemical weapons have been used and who used them," he said. "The international community can take actions based on those results."
